Principal neurons are colored red and synapses are numbered. Cones make synapses with two classes of cone bipolar cell (CB): ON and OFF CBs. ON and OFF CBs make excitatory synapses with ganglion cells (GCs), the output cells of the retina.
(1) Rods make synapses with an ON bipolar cell, the rod bipolar (RB), and with a subset of OFF CBs (not shown). Gap junctions between rods and cones are not illustrated (Raviola & Gilula, 1973; DeVries & Baylor, 1995).
(2) RBs contact AII amacrine cells.
(3) AIIs are coupled by gap junctions to some types of ON CBs and to other AIIs.
(4) ON CBs make synapses with ON GCs.
(5) AIIs make inhibitory glycinergic synapses with some OFF CBs and OFF GCs.